The use of optical fibers as a medium for transmission of digital data (including voice data) is becoming increasingly more common due to the high reliability and large bandwidth available with optical transmission systems. Fundamental to these systems are optical assemblies for transmitting/receiving optical signals and multiplexing/demultiplexing signals. The manufacture of these optical assemblies, however, tends to be difficult, expensive, and time consuming.
One of the primary technical challenges associated with the manufacture of optical assemblies, especially systems offering higher levels of integration, is component optical alignment. This is especially applicable in free-space, interconnect optical systems where discrete optical components, such as active devices (e.g., semiconductor lasers), passive devices (e.g., filters), and/or MOEMS (micro-optical electromechanical systems) (e.g., tunable filters and switches) are integrated on a common mounting system to exacting tolerances, typically in the sub-ten micrometer down to sub-micrometer range. These optical mounting systems, sometimes referred to as “optical benches,” provide a rail or platform to facilitate the mounting of various optical elements in fixed relationship to achieve optical alignment.
For components to be optically aligned, they must be held in a precise spacial relationship with respect to each other along the x, y, and z axes. (The z-axis is, by convention, the optical axis.) There are generally two alignment approaches for aligning optical components on a platform —active and passive. In passive alignment, registration or alignment features are typically fabricated directly on the components as well as on the platform to which the components are to be mounted. The components are then positioned on the platform using the alignment features and affixed in place. In active alignment, the optical components are placed on the platform, but before being affixed thereto, an optical signal is transmitted through the components while they are manipulated to provide optimum optical performance. Once optimum performance is achieved, the components are affixed to the platform. Although active alignment tends to be more precise than passive alignment, passive alignment facilitates high-speed, high-volume automated manufacturing and, thus, is preferred. It tends to be exceedingly difficult, however, to optically align in all three axes using passive alignment, especially if exceptionally good alignment is required. Nevertheless, a significant reduction in manufacturing time and costs can be realized if passive alignment can be used to achieve acceptable alignment along two axes or even one so that active alignment is only necessary for the remaining axes or for fine tuning.
Therefore, a need exists for an optical mounting platform which eliminates or reduces the need for active alignment but which is precise down to the submicron range. The present invention fulfills this need among others.